Scientists and conservationists are making a last-ditch effort to block the West Australian Government's plan to extend its controversial shark cull for three years.

The cull targets white, tiger and bull sharks at beaches off Perth and the state's southwest in a programme aimed at reducing the threat of attacks on swimmers, surfers and divers.

Submissions on the state Environmental Protection Authority's review closed on Monday with little sign of second thoughts despite scientific assessments panning the cull, continuing protests and threadbare results from last summer's trial.

The review ignored conservationists because "their position was already known" and downplayed the role of science in policy decisions that placed perceptions of public safety above the views of experts.


It conceded that academics did not generally support the programme, although further research was needed.

"Perhaps the most prevalent criticism of the programme is that it is not based on science," the review said. "In considering this criticism, science indicates that fatal shark attacks are infrequent, and in Western Australia they are predominantly made by white sharks.

"However, science also cites the white, tiger and bull shark [the cull's targets] as responsible for most shark attacks, and that the number of unprovoked attacks is rising.

"Science alone will not provide the basis for the development of public policy. Rather, it informs public policy."

An international coalition of leading marine scientists and researchers has struck back, raising doubts about the science the WA Government has used and saying there is no evidence the cull is making the state's beaches safer.

A submission from more than 250 international experts - one of almost 7000 - challenged the science and effectiveness of the cull.

Among them was American marine biologist Elliott Norse, who worked for several US Presidents and played a key role in President Barack Obama's plan to extend the Pacific remote islands' national monument 225,000sq km marine national monument to cover 2 million sq km.

The monument, covering US island territories, protects many marine species, including sharks.

"I think killing apex predatory sharks like tiger sharks is a terrible idea," the ABC quoted Norse as saying. "Apex predators are really important in ecosystems and when we kill them what we often find is really bad things happen."

The WA Government also sidelined advice it commissioned from associate professor Daryl Mcphee, a leading environmental scientist at Queensland's Bond University.

Mcphee warned the cull's inevitable bycatch could further damage threatened marine species including dolphins, turtles and sharks and rays with no history of attacks on humans.

The Government has justified its rejection of the advice, given before the cull was launched, with data showing the bycatch of non-target species last summer was "low or non-existent", with no dolphins, whales or turtles caught. The only bycatch was seven rays and a northwest blowfish.

The review concluded that the risk to other species from an extension of the cull would be negligible.

The cull was launched amid furious opposition last year in response to a series of attacks that saw seven deaths in 3 years. Most were believed to have been by great whites, protected under federal law.

Drum lines were set about 1km offshore "to offer an additional shark hazard mitigation measure at select high-use swimming beaches and surf spots at peak times of the year".

The trial cull's results are hotly debated. Although the Government says the programme of baited drum lines probably reduced the number of sharks potentially threatening WA beaches, critics say it failed.

No great whites were among the 172 sharks caught. Most were tigers, and most that survived on the hooks were less than the required length of 3m and were released.

Great whites were targeted because they were responsible for 11 of the 20 fatal attacks off WA in the past century and were thought to be the most likely species in two further deaths. Tigers were confirmed as killers in two, with three probables. Only one fatal bull shark attack was recorded.

The Government also said the average annual rate of great white attacks in the state had more than doubled in the past 20 years, and data indicated they had increased, or at least stabilised, over the past decade.

But scientists argue that even if great whites are caught, the risk of attack will not be reduced.

Attacks are more likely to occur in deeper water: only one has been reported close to shore. Most sharks have struck more than 1km from land, with scuba divers and snorkelers, surfers and sea kayakers accounting for more than 80 per cent of attacks. Swimmers have suffered the least.

The final decision on the cull will rest with the federal Government, which suspended the great white's protected status to allow last summer's trial cull. Any move to extend the programme will require a new federal assessment and approval.